High speed optical scanning system



Aug. 18, 1970 T. A. HOSKINS HIGH SPEED OPTICAL SCANNING SYSTEM 2Sheets-Sheet 2 Filed Aug. 6, 1968 /POSITION l FIGB 3,524,928 HIGH SPEEDOPTICAL SCANNING SYSTEM Thomas A. Hoskins, Lexington, Ky., assignor toInternational Business Machines Corporation, Armonk, N.Y.,

a corporation of New York Filed Aug. 6, 1968, Ser. No. 750,599 Int. Cl.H04n .l/04

U.S. Cl.. 178-7.6 7 Claims ABSTRACT F THE DISCLOSURE A document scanningsystem is describedwhich allows successive scans to occur in rapidsuccession. This is FIELD OF THE INVENTION This invention relates to anopticalgscanning apparatus for transferring an image from a documentl toa moving electrostatic plate or drum or other image recording surface.

More particularly, this invention relates to an irnproved image scannerwherein the operation is especially adapted to rapid scanning of thesame document and thus allowing additional copies to be made rapidly.

In prior art devices, optical scanners are used to project the image ofa document upon a moving photo sensitive plate or drum. After one imagehas been projected upon the recording surface, the scanner returns tothe starting position. This return necessitates a return period withinthe operating cycle of the machine. As a consequence, the speed withwhich copies of a document can be made in prior art devices isrestricted by the time required to scan the document as well as the timerequired to return the scanning mechanism to the start position.

It is a particular object of this invention to improve the scanningspeed of a document copier.

It is another object of this invention to remove the necessity of arapid return of the scanning mechanism between successive scanningoperations.

It is an additional object to provide an optical scanner which isparticularly adapted to rapid scanning of the same document.

These and other objects are obtained through a scanning system whichemploys two possible optical paths.`

The unique optical scanner described in this invention has ytvyo opticalprojection means which are movable so as to project thedocument'imageuponraiiiiage storage means. The two projectors move inalternate converging and diverging motion while the required image ofthe two available images is selected by a shutter means. Thus,

3,524,928 Patented ug. 18, 1970 rice in the optical position at thebeginning of a first scanning operation;

FIG. 1b shows the apparatus in FIG. 1a at the cornpletion of the firstscanning operation;

FIG. 1c shows the apparatus in FIG. 1a at the beginning. of a secondscan operation;

FIG. 1d shows the apparatus in FIG.. 1a at the completion of the secondscanning operation;

FIG. 2 shows one of two preferred embodiments wherein the movableelement is a mirror;

f FIG. 3 shows a second preferred embodiment wherein the'm'ovableelement is a lens.

Referring now to the drawings, FIG. 1a shows a schematic diagram of theoptical scanning apparatus defined bythis invention -at a position justprior to a first scanningfoperation. It should be noted lthat theelements and operations depicted in FIG. 1 are presented as a symbolicapproach to explain the operation of the preferred embodiments shown inFIG. 2 and FIG.

In FIG. 1a a fixed document support 10 is shown 'having a first edge orleft edge 12 and 'alsecond edge or right edge 14. Document support means10` comprises any apparatus for supporting at a fixed position anydocument desired to be recorded upon image recording surface 24. Thedocument supportl means 10 might be a glass plate, a means forsupportingdocuments by their edg'be, or any other means for supporting adocument in the relative position as shown. i'

Elements 20 and 22 are movable image projection means. These projectorsare movable from the position shown in FIG. 1a in the direction of thearrows or in a converging motion toward each other. In FIG. 1b, movableimage projectors 20 and 22 are shown at the stop position after havingmoved in converging motion toward each other.

The function of the movable image projection means 20 and 22 is to scanthe document supported by the fixed document support means 10 from oneedge to the other edge. Movable image projection means 20 is used toscan the document from the first e'dge 12 to the second edge 14. Whenthe movable image projection means 20 is in the position as shown inFIG. 1q, the left edge 12 is projected into fixed image projection means16. When movable image projection means 20 has progressed to its fullestexten-t in converging motion,it will project the image from the rightedge 14 into fixed image projection means 16 as shown in FIG. 1b. Thus,as movable image projection means 20 moves from left (the position shownin FIG. la) to right (the position in FIG. 1b), the document supportedby document support means 10 is scanned from left edge 12 to right edge14. Movable image pro jection means 22, while moving in convergingmotion from the position shown in FIG. la to the position shown in FIG.1b, scans the document held by document sup-t port means 10 from theright edge 14 to the left edge 12. During the converging motion, each ofthe movable image projection means 20 and 22 project in a line by linefashion the image of a document supported by document support means 10into respective fixed image projection means 16 and 18 as shown by thedotted lines in FIGS. 1a and lb.

Fixed image projection means 16 collects the image from movable imageprojector 20 and projects the image upon the recording means 24. Fixedimage projection means 16 functions to focus the changing image as pronjected Aby movable image projection means 20 upon the image recordingm'eans 24. Recording means 24, as shown in the drawings of thisapplication, appears as a drum. In fact, it could be a photo sensitivedrum. However, there are other possible forms the image recording means24 could take on namely, a moving photo sensitive plate a movingphotographic film on any other moving surface capable of recording anoptical image. Likewise, fixed image projection means 18 is alsofunctional to focus the image from movable image projection means 22upon image recording means 24. However, as shown in FIG. la, the imageprojected by fixed image projection means.'18 is blocked by imageselector 26. Thus, during converging motion as depicted in FIG. la andFIG. lb, the image as projected by movable image projection means 20isthe only image which is allowed to strike the image recording means24, causing the document supported by document support means 10 to berecorded upon the image recording means 24 starting from left edge 12and progressing to right edge 14 when the movable image projectors arein converging motion.

When the scanning apparatus has come to a rest at the position shown inFIG. 1b, the converging motion -scan is complete. In order for a secondscan operation to begin, image selection means 26 must be moved in thedirection 4 as shown in FIG. lb so as to reach a final position as 2Oshown` in FIG. lc. Thus, image selection means 26 moves from selectingthe image from fixed image projection means 16 as shown in FIG. 1b toselecting the image pro jected -by fixed image projection means 18 asshown in FIG. lc. With the movement of image selection means 26 25 fromthe position of FIG. 1b to FIG. 1c, a second scan- :ning operation maybegin.

The second scanning operation is one wherein the movable imageprojection means 20 and 22 move in diverging motion, each in thedirection of the arrow as shown in 30 FIG. lc. During diverging motion,image projection means .22 will scan the document from the left edge 12to the right edge 14 as depicted by the drawings 1c and 1d. During thisperiod of diverging motion, moving image projector means 20 is returningto the start position and 35 scanning the document from right edge 14 toleft edge 12, however, the image is blocked from striking image recording means 24 by image selection means 26.

At the completion of the diverging motion mode, the document supportedby `fixed document support means 10 40 has been scanned from left edge12 to right edge 14 through movable image projection means 22 and fixedimage projection means 18 and has come to the position as shown in FIG.ld. Thus, in order to begin the next scanning operation, the imageselection means 26 must be 45 moved in the direction as shown in FIG. ldto the posi-1' tion as shown in FIG. la. With the movement of imageselection means 26 to the position as shown in FIG. la, the convergingmotion mode .may begin again.

Thus, during converging motion, one of the movable 50 image projectionmeans is allowed to project the docuu ment supported by document supportmeans 10 upon image recording means 24. Upon completion of the'con=;verging motion, the image selection means 26 is changed; so as to allowthe image of the second movable image 55 projection means to beprojected upon image recording):l means 26. Thus, during divergingmotion, the document; is scanned by a second movable image projectionmeans in the same direction as the image was scanned during theconverging motion mode. The speed of scanning docu- G ments in anoptical scanner is, therefore, enhanced because the only time delaybetween one scan operation and the other is caused by the changing ofthe image selection means from one position to another, rather than, asin prior art devices, returning the whole scanner to 6D a start.position. Since the image selector can be operated at very high speeds,the delay between one scan and another is very small.

It should be further noted that the scanning mechanism herein described.comprises only a small portion of document copying machine. Typically,there will be additional processing stations past which the revolvingrecording means 24 will pass. These stations, not shown the drawings,are required to transform the recorded 75 image upon recording means 24into a visual image which is to be presented to the user.

FIG. 2 shows one alternate embodiment. Movable mir rors 42 and 44perform the function of the movable image projection means and 22 asshown in FIG. l. The image of the document held by document supportmeans is reflected from movable mirrors 42 and 44 through lens 46. Oneof the two optical image paths is blocked by shutter means 48. Shuttermeans 48 is a semicircular disc mounted upon a shaft so as to allow theshutter means 48 to block the optical path from either movable mirrorbut not both at the same time. The image not blocked, passes through thelens and reflects from fixed mirror 50 or 52 depending upon the positionof shutter means 48. The image refiected from the fixed mirror isfocused upon the image recording surface 56. Light shields 54 and 68form a narrow slit-like opening along the length of the image recordingsurface 56, and only allow light passing through the slit to expose theimage recording surface 56. The width Ibetween the two light shield elements must be small so asto focus only a smallportion of the documentupon the image recording surface, the smaller the opening the sharperthe image recorded.

Movable mirrors 42 and 44, while at position 1, are at the beginningpoint of a converging motion scan opn eration. During a convergingmotion scan operation, move able mirrors 42 and 44 converge toward eachother from position 1 to the final stop position, position 2. With theshutter means 48 in the lposition as shown, the document upon documentsupport means 40 is effectively scanned from the right edge to the leftedge. When shutter means 48 is rotated 180 clockwise about the axis 60,the optical scanner is ready for a second scan operation or a divergingmotion scan. During a diverging motion scan, movable mirrors 42 and 44diverge from each other from. position 2 to a final stopping position,position 1. After a diverging motion scan, returning shutter means 48 tothe position as shown in FIG. 2 prepares the optical scanner for asubsequent converging motion scan operaD tion. Thus, during convergingmotion, the document supn ported by document support means 40 is scannedfrom right to left 4by movable mirror 44 and during diverging motion thedocument is scanned from right to left by movable mirror 42.

FIG. 3 shows a second embodiment of this invention. Document supportmeans holds the document such that the movable lens and fixed mirroroptical system can focus the image of the document upon recordingsurface 88. Movable lenses 72 and 74 are shown in a position prior to adiverging motion scan operation, at position 1. During a divergingmotion scan operation, shutter means 90 is positioned such that theimage projected from movable lens 72, fixed mirror 76, and fixed mirror82 is blocked from striking the image recording means 88. The documentwill be scanned during a diverging motion scanning operation from leftto right, the image being projected upon image recording means 88 bymovable lens 74, fixed mirror 78, and fixed mirror 80. Light shields 84and 86 provide a small slit-like opening and allow only a small portionof the image of the document to be focused upon image recording means88. At the end of a diverging motion scan operation, the movable lenses72 and 74 are stopped at position 2. When shutter means 90 is pivotedclockwise about axis 92, the

image as projected by movable lens 72, fixed mirror 76,

and fixed mirror 82 is projected upon image recording means 88 while theoptical path through movable lens 74, fixed mirror 78, and fixed mirroris blocked. A converging motion scan, movable lenses 72 and 74 mov- 0ing from position 2 to position 1, allows the document to be scannedfrom left to right. Thus, during diverging motion, the document isscanned from left to right through the optical path comprising movablelens 74, fixed mirror 78 and fixed mirror 80 and during convergingmotion. the document is scanned from left to right through the andixedminori-82."

.Through the use of movable mirrors or movable lenses, .a 4'high lspeedshutter mechanism, and other -opticalelements, a' high speedvop'ticalscanner can be fproduced edge and capable of projecting saiddocunieritfupon said image recordin'i surface while said secorid im'pgeprojection system 's'c'ans 'said document fr msaid first edge to saidsecond edge and projects v ment upon said recording ,surface during`-scan mode;`and f an image selection means for allowing the imageprojee-ted by said first image projection systemto strike said imagerecording surface while preventing the document from said first edge tosaid second edge and -projectsj said document upon said image re=cording surface Vwhile said second imagey projection. system scansw saiddocument-'from said second edge to'said vfirsjj edge and capable ofprojectingv said which eliminates the ne essity of the rapid jtrfpeturn,0f document upon said image recording surface during optical scanningmechfw sms found in curr'e i optical a first scaniiode, and for movingsaid movable opcopiers. While the inveifttion has been particulafglyshown tical po'rtioffA o that said first image projectiori sysanddescribed Wl'll fefll'ell t0 plefCl-I'd emlgdlmetS ltern Scans dogumentfrom said second edge t0 thereof, it'will heundegstood by those7'skilledjirii the 'art 10 vsaid first edge and capable of projectingsaid docuthat-'Various Changes IOIIH and details maybe made ment upon`-"said image recording surface whilei'said ,therein without departingfrom the spirit and vscope of second imaglA projection system scans saiddocument this invention. 1 l 11;; from said first edge to said secondedge and 'projects For'exampl'e, the movable image projection means assaid document upon said recording surface during shown in FIGS.. 1-3move in 'a plane parallgl to; the 15 a second scaii mode; and u documentsupport. It will be readily recogriizedl'fbyhose an image selegtionmeans for allowing the image pro= skilled in the art, thatr'odificationsto the optcalsystpm jected by first image projection system to strike`can easily be made suoli that "the movable image .projecsaid imager'ecording surface while preventing:y the tion means will movealgng'paths, which may linesvor image projefc'ted by said second imageprojection arcs,not parallel to-thxef' support means. In agvcli'tiqn;vit 20 system fro striking said image recording surface will berecognized by those skilled Iin the argl? tlattfthc during saidjwfirstscan mode, said image selection document support need ot be a fiatsurface. 'jllowever, means operable to allow the image projected by saidif such a modiflcationzgis m'ade, additional agpigopriate second imageprojection system to strike said image modifications must be made to theoptical paths.; invorder recording sur ace while preventing the imageproto insure proper functioning of this invention. 25 jected by s :aiidfirst image projection system from what is Claimed is Y i striking saidimage recording surface during Lysaid l.. An optical device for scanningdocuments com- Second Sca de. i, prising': l' 3. An opticaldevice forscanning documents come afixed document support means for holding adocuprising; Si 5 "ment, Said .dmif SPPOY'I m'e'DS havjigdilv r'St 30 afixed document support means for holding a docu= y and Second edge, fh'edgf t Opposite ends 0f Sald ment, said isi'ipport means having a firstand second document SUPPOIt gleam; u 'r' "edge, each dge at oppositeends of said fixed docue a first Aand 'second irilage projectionsystemgvwr ment Suppdt means; all image leCOl'dlflg ,Sjlffa n i afirstand seicind fixed image projection means; means for movmg'sig mage Prolectlon sySimS Suih 35 a Afirst and seicond movable image projectionmeans,

that Said rS'lmgePfOeClOIl SYSFm S-91d ".-fi'said first rrohvable imageprojectionmeans for pro-v documfe. fr onf sadfst edge t0 s ald Secondedge jecting the A``mage of a document supported by said and PTOJeCtSSald d-Shlcument upon Sald ma recom' fixed docu t support means intosaid first fixed ing surface while Sdgd Second image Projet n, SXSW. 40'image lproj ,tion means, said secondmovable image Scanssald documeP fromsa@ Scond ed S-ad projection eans for projecting the image of a docuzrst .edge fimd apbl? ,of proectmg 5.a1d d mint ment supported by saidfixed document support upon Sad Image reerdmg sllrface dnl-.mgaifist Sanmeans into`4` said second fixed image projection mode, Iand for;inioyming said image projecticrri systems means. l such t at sai rsti imae projection syslem vscans a Said document .froll Sai second edgetonasai @ist s means for moying said first movable image projectionmeans so to scan theimage of said document from said f irst edge to saidsecond edge while said second moiiible image projection means is movableso as to sc the image of said document fromsaid second edg o said firstedge, both movements oc-1 curring sing ltaneously during vva first scanmode, arid for moving` said first movable image projection means so asto scan said document from said second edge to said first edge whle'saidsecond movable image projected by said second image projection imageprojection means is movable so as to scans'aid system from striking saidimage recording `surface l document from said first edge to said secondedge, during said firstv scan mode, said image SeleCtiOIl l j bothmovements occurring simultaneously during a A means..operable to allowthe image projected bysaid Second man mode;

second image projection system to strike said image an image teem-dingmeans; recording surface while Prevenlng the image 121'0' 60 a selectionmeans, said selection means being posi= J'e'ted by Said first imagePr-olecton system *fr-Dfi; tioned to allow projection ofthe image of-"said docurlllgscldrglge recording surface duid??r sf i mentthrough saidyfirst fixed image means 2. An optical deyice for scanning documentscomio sald -lmilgevrofdmg ,means While blocking the prising: .l l Y Vimage projectedlgby ysaid second fixed image pro a .fixed documentsupport means -for holding adocu-l ment, saiddoeumen'tsupport'meanshaving a`=first` and second edge, each edge at opposite ends of `saidv Ydocument supportmeans;

a first andl second image projectionv system,`esach sysv'v ls aidrfirstfixed image projection means during said jection means during said'vfirst scan mode, said selec= tion means being positioned toallowprojection of Us'pcoiid scan inode..

animagexrg-eemng Surfac'v" f v ,.y.j'di'iihelopticalsdeviceforscanningdocuments of claim means for moving said movable optical portionsso 13g-wh ein said first and second movable image projection thatsaid first image projection system scans said ey meansare eachalens.

ments of claim 3 wherein said first and second movable' image projectionmeans are each a mirror.

6. -An optical device for scanning documents comprising: 1

a xed document support means for ment;

a first and second image reiiection means;

means for moving said first and said second image reflection means inalternate converging and diverging motion, said first and second imagereflection means providing two optical paths for the image of saiddocument;

an image recording surface;

focusing means located between said first and second image reectionmeans and said: image recording surface for focusing the image from eachof said two optical paths upon said image recording surface; and Y aselecting means for selecting which of two optical paths is to beprojected upon said image storage means, said selection meansoperational to select the path from said first image reliection meansduring said converging motion and operational to selectthe path fromsaid second image reflection means during said diverging motiona `Anoptical device for scanning documents comprising:

a fixed document support means for holding a docu nient;

a first and second focusing means;

holding a documeans for moving said first and second focusing means inalternate converging and diverging motion, said first'and secondfocusing means producing two op1 t ticalflpaths for the image of saiddocument;vv an image recording surface; asretiecting means locatedbetween said'first and secc ond focusing means and said image recordingIsurface; said refiecting means operational to reflect the imag'es ofsaid two optical paths upon said image recofding surface; and gselecting means for selecting which of said two optical l `jpaths are to-be directed upon said image storage means, said selection meansoperational to select the optical path from said first focusing meansduring said converging motion and operational to select the optical pathfrom said second focusing means during said diverging motiont,v

= i References :Cited UNITED STATES PATENTS ROBERT L. GRIFFIN, PrimaryExaminer J. A. oRsINo, in, Assistant Examiner

